In machines having components moving along redundant axes, a target position of a tool can be reached by various combinations of the movements along the redundant axes. For example, one machine component can be the sluggish (heavy) coarse axis component, having a large range of motion along the axis for movement over the workpiece (in the order of magnitude of meters) and another component, which can be highly accelerated, can be the (light) fine axis component having a small range of motion (in the order of magnitude of several centimeters to a few tens of centimeters) over the same axis. Movement in the components along the axis in concert can allow rapid travel down fine contours. In sheet mover laser cutting machines, in which both the workpiece and also the laser processing head are moved along redundant axes, the component for movement of the sheet acts as the coarse axis component and the component for movement of the laser head acts as the fine axis component.
German Patent Publication DE 103 55 614 A1 discloses filtering a target path using a low-pass filter and supplying the filtered target path to the coarse axis component to obtain target positions along the axis for each component so that the combined motion of the components produces the target path of laser processing. The difference between the filtered target path and the actual target path results in the target path for the fine axis component. The target values, which are strongly smoothed by the low-pass filter, are thus supplied to the less dynamic coarse axis component, and the difference between the smoothed target values of the coarse axis component and the target values of the axis pair are supplied to the more dynamic fine axis component. The target path is supplied to the system only after a delay to minimize the range of motion of the fine axis component, which enables higher accelerations for this component along the axis. The target path of the coarse axis component is thus closer to the target path of the overall system.
As a result of the properties of path division methods, in machines having redundant axes, the individual axes of the redundant axis pair also continue to run when the superimposed movement of the redundant axes is already completed. The two axes of the axis pair move in opposite directions in this case. In sheet mover laser cutting machines, however, this property permits the remaining sheet to continue moving when the workpiece section has already been cut out. The risk of overlapping or entangling thus exists between the cut-out workpiece section and the remaining sheet. One approach to deal with this issue is to stop the redundant axes in a timely manner before the cutting-out end position and then, with a stationary sheet, only execute the severing cut of the last contour section, the so-called “final cut,” using the fine axis. However, this procedure consumes a relatively large amount of time.